The most popular by a landslide: Snapchat.

It's no surprise that teenagers love Snapchat. Here's what they had to say about it:

"It's how I communicate with most of my friends and it's fun." — a 15-year-old

"Snapchat because it's pretty much just texting, but with pictures of my beautiful face " — a 16-year-old

"Snapchat, because it is fun to send your friends what you're doing, and where you are in a fast and easy way. I also like being able to make stories, for all of my friends to see, and I also enjoy seeing stories of my friends on it and see what they're up to." — a 17-year-old

The dark horse: Twitter.

Anthony Quintano/Flickr

You might not expect Twitter to be among teens' favorite apps. After all, the company is having a hard time attracting new users. But a lot of teenagers we talked to really liked the platform. Here what they had to say:

"Twitter because I can update everyone all the time quickly and it's not annoying like Facebook." — a 17-year-old

Twitter because "you can voice your opinion on anything you want to and you can somewhat interact with celebrities." — a 18-year-old

"My favorite app is Twitter because I am the kind of person who needs to get out my thoughts, and Twitter may be like shouting into the void but at least I am heard and often validated by my peers." — a 19-year-old

Facebook may be dead to teens, but a surprising number of them are texting their friends through Facebook Messenger.

Facebook

The most common form of messaging among teenagers in our survey was iMessage or SMS messaging — 100% of the teens we talked to used one or both of those.

But Facebook Messenger was mentioned almost as frequently — 80% of teenagers we spoke with said they used Facebook Messenger as a primary or secondary form of communicating with friends. Less popular were WhatsApp, Kik, and Snapchat text.

After School.

iTunes

Several teens brought this app to our attention. We first wrote about After School, a social network created specifically for high-school students, when it launched and started gaining traction in late 2014.

If you're nervous thinking about the kinds of stuff teenagers would post anonymously on a social network, you're not alone. Millions of teens are using it to post their "deepest anxieties, secret crushes, vulgar assessments of their classmates, and even violent threats," according to The Washington Post.

Musical.ly.

Screenshot

You've probably never heard of Musical.ly, but it has already cracked the top 20 in Apple's App Store. The app has quietly grown to its popular status without any press.

Musical.ly lets you make music videos of yourself or of other people. It may not seem like a particularly compelling value proposition, but 10 of the 60 teens we spoke with listed Musical.ly as the app they were most excited about and doubted adults would know about.

Wishbone.

Wishbone

Launched by the Los Angeles venture-capital firm Science's mobile studio, Wishbone shows you two options and lets you vote on which one you like more— a spin on the popular "Would you rather?" hypothetical question.

"Neko Atsume."

Screenshot

You have probably never heard of the Japanese game "Neko Atsume," but numerous teens we talked to were obsessed with it. The game's name literally translates to "cat collecting," and that's exactly what you do in the adorable game.

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